diff --git a/generate-swagger.js b/generate-swagger.js
index 93cffab1..a9acb251 100644
--- a/generate-swagger.js
+++ b/generate-swagger.js
@@ -3,6 +3,7 @@
 'use strict'
 
 const parseArgs = require('./args')
+const argv = require('yargs-parser')
 const log = require('./log')
 const {
   exit,
@@ -24,6 +25,7 @@ function loadModules (opts) {
 
 async function generateSwagger (args) {
   const opts = parseArgs(args)
+  const extraOpts = argv(args)
   if (opts.help) {
     return showHelpForCommand('generate-swagger')
   }
@@ -45,7 +47,11 @@ async function generateSwagger (args) {
       process.exit(1)
     }
 
-    return JSON.stringify(fastify.swagger(), undefined, 2)
+    if (extraOpts.yaml) {
+      return fastify.swagger({ yaml: true });
+    } else {
+      return JSON.stringify(fastify.swagger(), undefined, 2)
+    }
   } finally {
     fastify.close()
   }
diff --git a/help/generate-swagger.txt b/help/generate-swagger.txt
index 1958a5cc..06ebf355 100644
--- a/help/generate-swagger.txt
+++ b/help/generate-swagger.txt
@@ -1,3 +1,8 @@
 Usage: fastify generate-plugin [opts] <file> [--] [<plugin-options>]
 
-Generate Swagger/OpenAPI schema for a project using @fastify/cli.
+Generate Swagger/OpenAPI schema for a project using @fastify/swagger.
+
+OPTS
+
+  --yaml=true
+      generate in YAML format
diff --git a/test/generate-swagger.test.js b/test/generate-swagger.test.js
index b97566b7..5e98e167 100644
--- a/test/generate-swagger.test.js
+++ b/test/generate-swagger.test.js
@@ -16,3 +16,14 @@ test('should generate swagger', async (t) => {
     t.error(err)
   }
 })
+
+test('should generate swagger in yaml format', async (t) => {
+  t.plan(1)
+
+  try {
+    const swagger = await generateSwagger(['--yaml=true', swaggerplugin])
+    t.ok(swagger.startsWith('openapi: 3.0.3'))
+  } catch (err) {
+    t.error(err)
+  }
+})
diff --git a/test/swaggerplugindir/plugin.js b/test/swaggerplugindir/plugin.js
index 80ef2594..fee6af1e 100644
--- a/test/swaggerplugindir/plugin.js
+++ b/test/swaggerplugindir/plugin.js
@@ -3,31 +3,53 @@
 const fp = require('fastify-plugin')
 
 module.exports = fp(function (fastify, opts, next) {
-  fastify.decorate('swagger', function () {
-    return {
-      openapi: '3.0.3',
-      info: {
-        version: '8.1.0',
-        title: '@fastify/swagger'
-      },
-      components: {
-        schemas: {}
-      },
-      paths: {
-        '/': {
-          get: {
-            responses: {
-              200: {
-                description: 'Default Response'
+  fastify.decorate('swagger', function (opts) {
+    if (opts && opts.yaml) {
+      return `\
+openapi: 3.0.3
+info:
+version: 8.1.0
+title: "@fastify/swagger"
+components:
+schemas: {}
+paths:
+"/":
+  get:
+    responses:
+      '200':
+        description: Default Response
+"/example/":
+  get:
+    responses:
+      '200':
+        description: Default Response
+`
+    } else {
+      return {
+        openapi: '3.0.3',
+        info: {
+          version: '8.1.0',
+          title: '@fastify/swagger'
+        },
+        components: {
+          schemas: {}
+        },
+        paths: {
+          '/': {
+            get: {
+              responses: {
+                200: {
+                  description: 'Default Response'
+                }
               }
             }
-          }
-        },
-        '/example/': {
-          get: {
-            responses: {
-              200: {
-                description: 'Default Response'
+          },
+          '/example/': {
+            get: {
+              responses: {
+                200: {
+                  description: 'Default Response'
+                }
               }
             }
           }